Question

помогите решить 2 вариант

Answer 1

▪1
а)
$\frac{15 x{y}^{4} }{10 {x}^{3} {y}^{2} } = \frac{3 {y}^{2} }{2 {x}^{2} } = 1.5 \frac{ {y}^{2} }{ {x}^{2} }$
б)
$\frac{ab - b}{ {b}^{2} } = \frac{b(a - 1)}{ {b}^{2} } = \frac{a - 1}{b}$
в)
$\frac{4 {x}^{2} - {y}^{2} }{2x - y} = \frac{(2x - y)(2x + y)}{2x - y} = 2x + y$
▪2
а)
$\frac{3}{a} + \frac{a - 3}{a + 5} = \frac{3(a + 5) + a(a - 3)}{a(a + 5)} = \frac{3a + 15 + {a}^{2} - 3a}{ {a}^{2}+ 5a } = \frac{15 + {a}^{2} }{ {a}^{2} + 5a }$
б)
$\frac{2 {x}^{2} }{ {x}^{2} - 4 } - \frac{2x}{x + 2} = \frac{2 {x}^{2} - 2x(x - 2) }{ {x}^{2} - 4 } = \frac{2 {x}^{2} - 2 {x}^{2} + 4x}{ {x}^{2} - 4 } = \frac{4x}{ {x}^{2} - 4}$
в)
$\frac{7a}{a - b} - 7 = \frac{7a - 7(a - b)}{a - b} = \frac{7a - 7 a + 7b}{a - b} = \frac{7b}{a - b}$

▪3
$\frac{5}{ {(a + 2)}^{2} } - \frac{5}{ {a}^{2} - 4 } - \frac{5}{a + 2} = \frac{5(a - 2) - 5(a + 2) - 5(a + 2)(a - 2)}{ {(a + 2)}^{2} \times (a - 2)} = \frac{5a - 10 - 5a - 10 - 5 {a}^{2} + 20 }{ {(a + 2)}^{2} \times (a - 2)} = \frac{ - 5 {a}^{2} }{({a}^{2} + 4a + 4)(a - 2) } = \frac{ - 5a}{ {a}^{3} + 4 {a}^{2} + 4a - 2 {a}^{2} - 8a - 8} = - \frac{ 5a}{ {a}^{3} + 2 {a}^{2} - 4a - 8 }$

▪4
$\frac{2a - 2c + ax - cx}{ {x}^{2} - 4 } = \frac{2(a - c) + x(a - c)}{ {x}^{2} - 4 } = \frac{(a - c)(2 + x)}{(x - 2)(x + 2)} = \frac{a - c}{x - 2}$
$... = \frac{a - c}{x - 2} = \frac{6.7 - 5.3}{1.9 - 2} = \frac{1.4}{ - 0.1} = - 14$